Sorting algorithm is one of the most basic research fields in computer science. It's goal is to make record easier to search, insert and delete. Through the description of five sort algorithms: bubble, select, insert, merger and quick, the time and space complexity was summarized. Furthermore, two categories of ( )O n n could be found out. From the aspects of input sequence scale and input sequence random degree, some results were obtained based on the experiments. When the size of records is small, insertion sort or selection sort performs well. When the sequence is ordered, insertion sort or bubble sort performs well. When the size of records is large, quick sort or merge sort performs well. Different application could select appropriate sort algorithm according to these rules.